Macrolide compounds endowed with antiinflammatory activity

ABSTRACT

The present invention relates to macrolide derivatives of formula (I) in which R 1  and R 2  have the meanings given in the description; which are endowed with antiinflammatory activity and are substantially free of antibiotic properties, to pharmaceutically acceptable salts thereof and to pharmaceutical compositions containing them as active ingredient.

The present invention relates to macrolides with antiinflammatoryactivity and, more particularly, relates to 3′-amide ketolides withantiinflammatory activity, to pharmaceutically acceptable salts thereofand to pharmaceutical compositions containing them as active ingredient.It is known that various antibiotics, in particular the class oferythromycin-based 14-atom macrolides, are endowed with antiinflammatoryproperties in addition to their antibacterial activity [Clin.Immunother., (1996), 6, 454-464].

Erythromycin is a natural macrolide (The Merck Index, 13th edition, No3714, page 654) that has displayed very broad clinical use in thetreatment of infections caused by Gram-positive bacteria, a fewGram-negative bacteria or micoplasms.

The interest of the scientific community has recently turned towards theimmunomodulatory and antiinflammatory activities of erythromycin andderivatives [Journal of Antimicrobial Chemotherapy, (1998), 41, Suppl.B, 37-46].

Macrolides have been found to be effective in the treatment ofinflammatory pathologies such as panbronchiolitis [Thorax, (1997), 52,915-918], bronchial asthma [Chest, (1991), 99, 670-673] and cysticfibrosis [The Lancet, (1998), 351, 420].

The in vitro activity of macrolides was found to be particularlyeffective in modulating the metabolic functions of a number of immunesystem cells such as neutrophils [The Journal of Immunology, (1997),159, 3395-4005] and T lymphocytes [Life Sciences, (1992), 51, PL231-236] and in modulating inflammation mediators such as interleukin-8(IL8) [Am. J. Respir. Crit. Care Med., (1997), 156, 266-271] orinterleukin-5 (IL-5) [patent applications EP 0 775 489 and EP 0 771 564in the name of Taisho Pharmaceutical Co., Ltd].

Neutrophils in particular are the first cell line recruited at the siteof infection or of tissue lesion in the early stages of an inflammatoryresponse.

A non-physiological accumulation of neutrophils in the inflamed tissue,their activation, the subsequent release of proteases and the increasein the production of reactive oxygen metabolites characterize a fewforms of inflammatory response which, most often, degenerate intopathological conditions.

Thus, although neutrophils are essential in immune defense and in theinflammatory process, it is known that they are involved in pathologiesderived from the majority of chronic inflammatory conditions andischaemic reperfusion lesions (Inflammation and fever; Viera'Stvrtinovà, Jan Jakubovsky and Ivan Hùlin; Academic Electronic Press,1995).

The same paper discloses pathologies for which the influence of impairedfunctionality of the neutrophils during their genesis and/or developmentis confirmed: among these, mention is made of atherosclerosis, ischaemicreperfusion damage, rheumatoid arthritis, psoriasis, vasculitis andautoimmune-based glomerulonephritis, Crohn's disease and chronicpulmonary inflammations such as ARDS (adult respiratory distresssyndrome).

COPD (chronic obstructive pulmonary disease) is a chronic pathologycharacterized by inflammation and gradual destruction of the pulmonarytissue caused by the massive presence of activated neutrophils withconsequent release of metalloproteases and an increase in the productionof oxygen radicals [Am. J. Respir. Crit. Care Med., 1996, 153, 530-534][Chest, 2000, 117 (2 Suppl.), 10S-14S].

The administration of macrolides to asthmatic individuals is accompaniedby a reduction in the hypersecretion and bronchial hypersensitivityconsequent to their anti-oxidative and antiinflammatory interaction withphagocytes and in particular with neutrophils; this interaction isthought to impede many bioactive lipids, involved in the pathogenesis ofbronchial asthma, from carrying out their pro-inflammatorymembrane-destabilizing activity (Inflammation, Vol. 20, No. 6, 1996).

Treatment with erythromycin, at low doses for long periods, is describedas being effective in reducing bronchial hypersensitivity in the case ofasthma sufferers (Miyatake H. et al Chest, 1991, 99, 670-673, alreadycited).

In another study, it is demonstrated that the same treatment, in thecase of COPD sufferers, can significantly reduce the frequency and therisk of exacerbation caused by acute respiratory infections (CHEST 2001,120, 730-733).

The results obtained are not attributable to the antibiotic activity ofmacrolides, but to the inhibition of the expression and release ofinflammatory cytokines.

This treatment, according to the abovementioned article, shouldpreferably be restricted to patients at high risk of exacerbation ofCOPD on account of the potential risk of development of resistantpathogenic strains.

The particular therapeutic efficacy of macrolides in pathologies inwhich conventional antiinflammatory drugs, for instance corticosteroids,have proved to be ineffective [Thorax, (1997), 52, 915-918, alreadycited] justifies the appreciable interest with regard to this novelpotential class of anti-inflammatories.

However, the fact that standard macrolides have potent antibacterialactivity does not allow their broadened use in the chronic treatment ofinflammatory processes not caused by pathogenic microorganisms; thereason for this is that this may give rise to the rapid development ofresistant strains.

It would therefore be desirable to have available novel substances witha macrolide structure that show antiinflammatory activity and that aresimultaneously free of antibiotic properties.

For greater clarity, the formula of erythromycin is given, in which isindicated the numbering adopted in the present patent application.

A number of classes of erythromycin derivatives with antibacterialactivity are described in the literature.

In particular, telithromycin (The Merck Index, 13th edition, No 9199,page 1627) is a semisynthetic derivative of erythromycin A and is thefirst molecule belonging to a new family of broad-spectrum antibacterialagents closely related to macrolides, which are known as ketolides.

Telithromycin is used as a second-choice treatment in community-acquiredinfections sustained by penicillin-resistant and macrolide-resistantstrains, in particular by group A beta-haemolytic streptococci and isalso active against intracellular and atypical bacteria.

Patent application WO 99/16779 in the name of Abbott Laboratoriesdiscloses a number of classes of erythromycin-based ketolides modifiedin position 3′ and 6-O-substituted, and to salts and esters thereof,with antibacterial activity.

The literature also discloses a number of classes of erythromycinderivatives with antiinflammatory activity.

For example, the abovementioned European patent applications in the nameof Taisho claim erythromycin derivatives modified in positions 3, 9, 11and 12, as potent inhibitors of IL-5 synthesis.

The use of erythromycin as an antiinflammatory agent that acts byreducing the release of interleukin-1 by means of inhibiting themammalian glycoprotein mdr-P is claimed in patent application WO92/16226 in the name of Smith-Kline Beecham Corporation.

Patent application WO 00/42055 in the name of the present applicantdiscloses 3′-desdimethylamino-9-oxime macrolides endowed withantiinflammatory activity and lacking antibiotic activity.

Patent application WO 04/013153 in the name of the present applicantdiscloses macrolide derivatives free of cladinose in position 3, whichare endowed with antiinflammatory activity.

Patent application WO 04/039821 in the name of the present applicantdiscloses 9a-azalides free of cladinose in position 3, which are endowedwith antiinflammatory activity.

It has now been found, surprisingly, that ketolide derivativesstructurally modified on the dimethylamino group in position 3′ have noantibacterial activity and, at the same time, have pronouncedantiinflammatory properties.

In particular, we have found, surprisingly, a novel class oftelithromycin 3′-amide derivatives that are endowed withantiinflammatory activity and are substantially free of antibioticproperties.

One object of the present invention is thus compounds of formula

in whichR₁ is a group —X—R₃ in which

-   -   X is a group —C(═O)—, —C(═O)—O—, —C(═O)—N—, —SO₂— or —SO₂—N— and    -   R₃ is a hydrogen atom; a (C₁-C₁₀)alkyl group; a        (C₁-C₄)alkoxy(C₁-C₄)-alkyl group; a (C₅-C₇)cycloalkyl group; a        phenyl, a five- or six-membered heteroaryl containing from one        to three heteroatoms chosen from nitrogen, oxygen and sulfur, a        phenyl(C₁-C₄)alkyl group or a heteroaryl(C₁-C₄)alkyl group        optionally substituted with 1 to 3 substituents chosen from a        (C₁-C₄)alkyl group, a (C₁-C₄)alkoxy group and halogen; or a        chain of formula

—(CH₂)_(r)—Y—(CH₂)_(m)-A

-   -   -   in which        -   A is a phenyl or a five- or six-membered heteroaryl            containing from one to three heteroatoms chosen from            nitrogen, oxygen and sulfur, both optionally substituted            with 1 to 3 substituents chosen from a (C₁-C₄)alkyl group, a            (C₁-C₄)alkoxy group and halogen; or a group

-   -   -   in which        -   R₄ and R₅, independently of each other, are a hydrogen atom,            a (C₁-C₆)alkyl group, a benzyl, a (C₁-C₄)alkoxycarbonyl            group or a benzyloxycarbonyl group;

    -   Y represents O, S or NR₆ in which        -   R₆ is a hydrogen atom, a linear or branched (C₁-C₃)alkyl, a            (C₁-C₃)alkoxycarbonyl group or a benzyloxycarbonyl group;

    -   r is an integer between 1 and 3;

    -   m is an integer between 0 and 3;        R₂ is a hydrogen atom, a (C₁-C₆)alkyl group, a benzyl group or        has the meanings given for the substituent R₁,        and pharmaceutically acceptable salts thereof.

The compounds of formula I are antiinflammatory macrolides free ofantibiotic activity and are therefore useful in the treatment andprophylaxis of inflammatory pathologies.

A further object of the present invention is the use of a compound offormula I as a medicament, in particular in the treatment ofinflammatory pathologies.

The use of a compound of formula I in the preparation of a medicamentfor the treatment of gastrointestinal pathologies of inflammatorynature, for instance ulcerative colitis and Crohn's disease, ispreferred.

Specific examples of (C₁-C₁₀)alkyl groups are methyl, ethyl, n-propyl,i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl, 1-methylbutyl,2-ethylpropyl, 3-methylbutyl, 3-methyl-2-butyl, n-hexyl, heptyl, octyl,nonyl, decyl and the like.

The term “(C₅-C₇)cycloalkyl group” means cyclopentyl, cyclohexyl andcycloheptyl.

The term “halogen” means a fluorine, chlorine, bromine or iodine atom.

The term “5- or 6-membered heteroaryl containing from 1 to 3 heteroatomschosen from nitrogen, oxygen and sulfur” means heterocycles such aspyrrole, thiophene, furan, imidazole, pyrazole, thiazole, isothiazole,isoxazole, oxazole, pyridine, pyrazine, pyrimidine, pyridazine, triazoleand thiadiazole.

It is clear to those skilled in the art that the substitution withpartially or totally saturated forms of the heteroaryls and also thepresence of other substituents on the aromatic rings (phenyl orheteroaryl) envisaged in the meanings of R₁ and R₂ gives rise tocompounds that do not depart from the spirit of the invention.

Preferred compounds of formula I are those in which R₁ has the meaninggiven in formula I and R₂ is a hydrogen atom, a (C₁-C₆)alkyl group or abenzyl group.

Within this group, compounds in which R₂ is a (C₁-C₃)alkyl group areeven more preferred.

Belonging to this latter group, compounds that are also preferred arethose in which R₁ is a group —X—R₃ in which X is a group —C(═O)—,—C(═O)—N— or —SO₂— and R₃ is a hydrogen atom; a (C₁-C₆)alkyl group; a(C₁-C₄)alkoxy(C₁-C₄)alkyl group; a (C₅-C₇)cycloalkyl group; a phenyl, afive- or six-membered heteroaryl containing from one to threeheteroatoms chosen from nitrogen, oxygen and sulfur, aphenyl(C₁-C₄)alkyl group or a heteroaryl(C₁-C₄)alkyl group optionallysubstituted with 1 to 3 substituents chosen from a (C₁-C₄)alkyl group, a(C₁-C₄)alkoxy group and halogen; or a chain of formula

—(CH₂)_(r)—Y—(CH₂)_(m)-A

in whichA is a phenyl or a five- or six-membered heteroaryl containing from oneto three heteroatoms chosen from nitrogen, oxygen and sulfur, bothoptionally substituted with 1 to 3 substituents chosen from a(C₁-C₄)alkyl group, a (C₁-C₄)alkoxy group and halogen; or a group

in whichR₄ and R₅, independently of each other, are a hydrogen atom, a(C₁-C₄)alkyl group or a benzyl;Y represents O, S or NR₆ in which R₆ is a hydrogen atom or a(C₁-C₃)-alkyl group;r is an integer between 1 and 3; andm is an integer between 0 and 3.

Within the scope of this group, compounds that are even more preferredare those in which R₁ is a group —X—R₃ in which R₃ is a (C₁-C₆)alkylgroup; a methoxy(C₁-C₃)alkyl group; a (C₅-C₇)cycloalkyl group; a phenyl,a heteroaryl chosen from furan, thiophene, oxazole and pyridine, abenzyl or heteroaryl(C₁-C₄)alkyl group optionally substituted with 1 to3 substituents chosen from a (C₁-C₄)alkyl group, a methoxy group andhalogen; or a chain of formula

—(CH₂)_(r)—Y—(CH₂)_(m)-A

in whichA is a phenyl or a heteroaryl chosen from furan, thiophene, oxazole andpyridine, both optionally substituted with a substituent chosen from a(C₁-C₄)alkyl group, a methoxy group and halogen; or a group:

in whichR₄ and R₅, independently of each other, are a hydrogen atom or a(C₁-C₄)alkyl group;Y represents O, S or NR₆ in which R₆ is a hydrogen atom;r is an integer between 1 and 3; andm is an integer between 0 and 2.

Within the scope of this latter group, compounds that are even morepreferred are those in which R₁ is a group —X—R₃ in which X is a group—C(═O)— and R₃ is a (C₁-C₄)alkyl group or a phenyl.

Examples of pharmaceutically acceptable salts of the compounds offormula I are salts with organic or mineral acids such as hydrochloricacid, hydrobromic acid, hydriodic acid, nitric acid, sulfuric acid,phosphoric acid, acetic acid, tartaric acid, citric acid, benzoic acid,succinic acid and glutaric acid.

Another preferred class of compounds that are the object of the presentinvention is that in which R₂ is a methyl, R₁ is a group —X—R₃ in whichX is a group —C(═O)—, —C(═O)—N— or —SO₂— and R₃ is a hydrogen atom, amethoxymethyl group, a cyclohexyl group, a phenyl, a benzyl, a4-methylphenyl, a 4-methoxyphenyl, a 4-fluorophenyl, a 2-furyl, a3-pyridyl, a 2-thienyl, a 2-chloro-3-pyridyl, a 2-thienylmethyl, a3-methyl-5-oxazolyl, a (4-methoxy-2-pyridylmethyl)oxymethyl group, aphenylthiomethyl group, an (N,N-dimethylaminoethyl)aminomethyl, methyl,ethyl, t-butyl or heptyl group.

The compounds:

-   3′-demethyl-3′-acetyltelithromycin; and-   3′-demethyl-3′-benzoyltelithromycin,    are also particularly preferred.

The compounds of formula I that are the object of the present inventionare prepared according to a synthetic scheme that involves demethylationof the dimethylamino group of telithromycin in position 3′, followed bythe amidation reaction of the primary or secondary amino group thusformed to give the compounds of formula I that are the object of thepresent invention.

The term “amidation reaction” means the operation for the introductionof the substituents X and R₃, defined in formula I in the meanings of R₁and R₂, in one or more synthetic steps.

The indications to implement the abovementioned structural modificationsto the ketolide derivatives are described more clearly hereinbelow.

Telithromycin is a known compound, which is commercially available andis prepared according to conventional techniques, for instance thosedescribed in patent EP 0 680 967 in the name of Hoechst Marion Roussel.

Starting with this substrate, the compounds of formula I are preparedvia demethylation of the dimethylamino group in position 3′ according toconventional techniques.

Thus, for example, telithromycin is treated with sodium acetate andiodine in the presence of an organic solvent as described in U.S. Pat.No. 3,725,385 in the name of Abbott Laboratories.

Alternatively, the said substrate is reacted with a dialkylazodicarboxylate in acetone as described in U.S. Pat. No. 6,433,151 inthe name of Aventis Pharma.

Functionalization of the primary or secondary amine group obtained inposition 3′ is performed via the use of amidation techniques known tothose skilled in the art.

In particular, these synthetic techniques relate to the commonpreparations of amides, sulfonamides, ureas, sulfonylureas and urethanesfrom an amine substrate.

As indicated previously, the amidation reaction is completed byintroduction of the substituents X and R₃ defined in formula I.

Generally, the substituents X and R₃ are introduced simultaneously ontothe macrolide molecule.

Thus, for example, the preparation of amide or sulphonamide derivativesis generally performed by treating the 3′-demethylated ketolide withsuitable acyl chlorides or sulfonyl chlorides according to conventionaltechniques, for instance reaction of the abovementioned compounds in thepresence of a base such as triethylamine and an organic solvent, forinstance dichloromethane or tetrahydrofuran.

In addition, the preparation of the urea derivatives is preferablyperformed via the use of suitable isocyanates in the presence of anorganic solvent, for instance dichloromethane.

Alternatively, the preparation of derivatives with structurally morecomplex amide chains is generally performed by synthesis according tostepwise processes.

Thus, for example, the 3′-demethylated derivative is treated with anomega-chloroalkanoic acid (acetic acid, propionic acid or butyric acid)and N-cyclohexylcarbodiimide in the presence of an organic solvent, forinstance tetrahydrofuran, and the compound obtained is used as asubstrate for the introduction of the end part of the amide chain, inparticular of the compounds of formula I in which X is a group —C(═O)—and R₃ is a chain of formula —(CH₂)r-Y—(CH₂)m-A.

The procedural choices will be determined, as and when necessary, bytechnical requirements finally having the purpose of optimizing thesynthetic process of the product under consideration.

As stated previously, the compounds of formula I that are the object ofthe present invention are endowed with antiinflammatory activity and arefree of antibiotic activity.

The pharmacological activity of the compounds of formula I was evaluatedin models of cutaneous inflammation compared with known macrolides suchas erythromycin, telithromycin and azithromycin, which are endowed withboth antiinflammatory activity and antibiotic activity.

The antiinflammatory activity was evaluated by means of inhibition ofthe oedema in mouse ear induced with PMA (phorbol myristate acetate).

In all the experiments, the compounds that are the object of the presentinvention were found to be very active as antiinflammatory agents andthe antiinflammatory activity was found to be greater than that of thecomparative compounds.

The antibiotic activity was evaluated “in vitro” as the capacity toinhibit the growth of bacterial strains sensitive to erythromycin andtelithromycin.

In particular, the antibiotic activity of the compounds was evaluated byturbidimetric assay in which the measurement of the bacterial growth isgiven by the increase in the turbidity/absorbance recordedspectrophotometrically in the culture broth.

The antibiotics erythromycin and telithromycin were used simultaneouslywith the test compounds as reference standards for the bacterialgrowth-inhibiting activity.

All the test compounds were found to be inactive towards bacterialgrowth, whereas, for the reference antibiotics erythromycin andtelithromycin, substantial inhibition of the bacterial developmentassociated with the concentrations used was measured.

The compounds of the present invention show no antibiotic activity andmay therefore be used in chronic treatments of inflammatory processeswithout giving rise to any undesired resistance phenomena.

It is thus obvious to a person skilled in the art that the compounds offormula I, which are endowed with antiinflammatory activity and are freeof antibiotic activity, may be useful in both acute and chronictreatment and in the prophylaxis of inflammatory pathologies, inparticular of pathologies related to impaired cell functionality ofneutrophils, for instance rheumatoid arthritis, vasculitis,glomerulonephritis, psoriasis, atopic dermatitis, ulcerative colitis,Crohn's disease, ischaemic reperfusion damage, septic shock,atherosclerosis, ARDS, COPD and asthma.

The therapeutically effective amounts will depend on the age and thegeneral physiological state of the patient, the route of administrationand the pharmaceutical formulation used; the therapeutic doses willgenerally be between about 10 and 2000 mg/day and preferably betweenabout 30 and 1500 mg/day.

The compounds of the present invention for use in the treatment and/orprophylaxis of the pathologies indicated above will preferably be usedin a pharmaceutical form suitable for oral, rectal, sublingual,parenteral, topical, transdermal and inhaled administration.

A further object of the present invention is thus pharmaceuticalformulations containing a therapeutically effective amount of a compoundof formula I or a salt thereof mixed with a pharmaceutically acceptablecarrier.

The pharmaceutical formulations that are the object of the presentinvention may be liquids suitable for oral and/or parenteraladministration, for instance drops, syrups, solutions or injectablesolutions that are ready for use or prepared by diluting a lyophilizate,but are preferably solid or semi-solid, for instance, tablets, capsules,granules, powders, pellets, ovules, suppositories, creams, pomades, gelsand ointments; or solutions, suspensions, emulsions or other formssuitable for inhaled and transdermal administration.

Depending on the type of formulation, in addition to a therapeuticallyeffective amount of one or more compounds of formula I, thesecompositions will contain suitable solid or liquid excipients ordiluents for pharmaceutical use and optionally other additives normallyused in the preparation of pharmaceutical formulations, for instancethickeners, aggregating agents, lubricants, disintegrants, flavouringsand colourings.

The pharmaceutical formulations that are the object of the invention maybe produced in accordance with conventional techniques.

The ¹H-NMR spectra were acquired in CDCl₃ or d₆-DMSO solutions, using aVarian Gemini 200 MHz spectrometer. The chemical shifts are reported inδ units using CHCl₃ or DMSO as internal standard.

The HPLC/MS analyses were performed using a Gilson machine containing aGilson Xterra RP18 column (5 μm, 4.6×50 mm) and using as detector a UVdiode array (220 nm), a Finnigan AQA mass spectrometer (electron spray,positive or negative ionization) and an ELSD detector.

Conditions used: flow rate: 1.2 ml/min; column temperature: 40° C.;elution gradient A/B (eluent A: 0.5% formic acid in water; eluent B:0.5% formic acid in acetonitrile): t=0 min., A/B=95:5, t=8 min.,A/B=5:95.

The examples that follow are now given for the purpose of illustratingthe present invention more clearly.

EXAMPLE 1 Preparation of 3′-demethyl-3′-acetyltelithromycin (Compound 1)

To a solution of 3′-demethyltelithromycin (200 mg, 0.25 mmol) andtriethylamine (70 μl, 0.5 mmol) in CH₂Cl₂ (3 ml) was added dropwise asolution of acetyl chloride (19.6 mg, 0.25 mmol) in CH₂Cl₂ (1 ml), andthe resulting mixture was stirred for 2 hours. The reaction mixture wasdiluted with ethyl acetate (50 ml) and the organic phase was washed with2N NH₄Cl (3×30 ml), 10% K₂CO₃ (2×30 ml), dried over anhydrous Na₂SO₄ andfiltered, and the solvent was evaporated off. Compound 1 (168 mg, 80%yield) was obtained as a white solid.

[M+1]⁺840.77;

HPLC-ELSD: Rt=4.63; purity 99.0%;

¹H-NMR (CDCl₃): δ 8.94 (d, 1H, J=1.7, C²H pyridine); 8.43 (dd, 1H,J₁=4.9, J₂=1.5, C⁶H pyridine); 8.06 (dt, 1H, J₁=8.0, J₂=2.0, C⁴Hpyridine); 7.52 (s, 1H, NCHN imidazole); 7.24-7.38 (m, 2H, C⁵Hpyridine+CHC imidazole); 4.9 (m, 1H); 4.36 (d, 1H, J=7.5); 4.20 (d, 1H,J=8.4); 4.00 (t, 2H, J=7.3, CH₂N_(imidazole)); 2.54 (m, 4H, CH₃N₊CH);1.24 (d, 3H, J=6.9); 0.98 (d, 3H, J=7.0); 0.81 (t, 3H, J=7.4; H₁₅).

EXAMPLE 2 Preparation of 3′-demethyl-3′-benzoyltelithromycin (Compound2)

To a solution of 3′-demethyltelithromycin (200 mg, 0.25 mmol) andtriethylamine (70 μl, 0.5 mmol) in CH₂Cl₂ (3 ml) was added dropwise asolution of benzoyl chloride (35.2 mg, 0.25 mmol) in CH₂Cl₂ (1 ml), andthe resulting mixture was stirred for 2 hours. The reaction mixture wasdiluted with ethyl acetate (50 ml) and the organic phase was washed with2N NH₄Cl (3×30 ml) and with 10% K₂CO₃ (2×30 ml), dried over anhydrousNa₂SO₄ and filtered, and the solvent was evaporated off. Afterpurification by Biotage chromatography (12M cartridge column, eluent100/5/0.5 CH₂Cl₂/MeOH/NH₃), compound 2 (205 mg, 91% yield) was obtainedas a white solid.

[M+1]⁺902.79;

HPLC-ELSD: Rt=5.38; purity 99.9%;

¹H-NMR (CDCl₃): δ 8.93 (d, 1H, J=1.9, C²H pyridine); 8.41 (dd, 1H,J₁=4.8, J₂=1.6, C⁶H pyridine); 8.05 (dt, 1H, J₁=8.1, J₂=2.0, C⁴Hpyridine); 7.51 (s, 1H, NCHN imidazole); 7.20-7.38 (m, 7H, C⁵Hpyridine+CHC imidazole+phenyl); 4.9 (m, 1H); 4.7 (m, 1H); 3.97 (t, 2H,J=7.3, CH₂N_(imidazole)); 3.53 (s, 1H, H₁₁); 3.05 (t, 2H, J=7.5, CH₂);2.86 (s, 3H, CH₃N); 2.59 (m, 4H, CH₂CH₂); 1.11 (d, 3H, J=6.9); 0.97 (d,3H, J=6.9); 0.80 (t, 3H, J=7.5; H₁₅).

EXAMPLE 3 In Vivo Pharmacological Activity A) Acute Contact Dermatitis

Animals

Groups of 5 CD1 mice (18-24 g) were used.

Administration of the Compounds

All the macrolide derivatives were dissolved in Trans-phase DeliverySystem (TPDS), a carrier containing 10% benzyl alcohol, 40% acetone and50% isopropanol.

15 microlitres of the compounds (500 μg/ear), dissolved in TPDS, wereapplied topically to the inner surface of an ear; 30 minutes later, 12microlitres of a solution of tetradecanoylphorbol acetate (TPA) at aconcentration of 0.01% dissolved in acetone were applied to the samearea.

Six hours later, the animals were sacrificed by inhalation of CO₂.

Evaluation of the Results

The degree of oedema was calculated by subtracting the weight of aspecified section of the untreated ear from that of the contralateraltreated ear. To determine the degree of remission of the oedema, theweight difference of the groups treated with TPA+macrolides was thencompared with the groups treated with TPA alone.

The activity of the macrolides was measured by using the modified methodof Zunic et al. (1998): MDL (Lysyl) GDP, a non-toxic muramyl dipeptidederivative inhibits cytokine production by activated macrophages andprotects mice from phorbol ester- and oxazolone-induced inflammation (J.Invest. Dermatol., 111(1), 77-82).

The results obtained for the compounds of formula I are given in Table 1below.

TABLE 1 Oedema Compound (% inhibition) Erythromycin 42 Azithromycin 40Telithromycin 79.7 1 81.7 2 81.8

EXAMPLE 4 In Vitro Pharmacological Activity A) Antibiotic Activity:

The antibiotic activity of the compounds was evaluated by means ofturbidimetric assay as described in the literature (Keller R., PedrosoM. Z. et al. Occurrence of virulence-associated properties inEnterobacter cloacae. Infection and Immunity, pp. 645-649, February1998), (Saiman L., Burns J. L. et al. Evaluation of reference dilutiontest methods for antimicrobial susceptibility testing of Pseudomonasaeruginosa strain isolated from patients with cystic fibrosis. Journalof Clinical Microbiology, pp. 2987-2991, September 1999).

The turbidimetric determination of the bacterial growth is given by theincrease in the transmittance/absorbance recorded spectrophotometricallyin the test culture broth. The antibacterial activity was evaluated asbeing the concentration of compound capable of inhibiting thedevelopment of a culture broth of the bacterial strain Escherichia coli(ATCC 25922) incubated in 96-well plates. The antibiotics erythromycinand telithromycin were used simultaneously with test compounds asreference standards for the bacterial growth-inhibiting activity. Thecompounds and the reference antibiotics were tested at 8 concentrationsobtained by means of 1:2 serial dilutions in the incubation plate,starting with a concentration of 100 μM.

Preparation of the Compounds:

For each test compound, a 200 μM concentration was prepared (doubledrelative to the incubation concentration), by diluting 10 μl of a 10 mMstock solution in DMSO, in 0.5 ml of Tryptic Soy Broth (TSB).

200 μl of the prepared solutions were distributed in a 96-well plateand, by means of 1:2 serial dilutions with TSB, the successiveconcentrations were obtained. The resulting plate at the end of thedilutions contained, in a volume of 100 μl/well, one compound per columnin 8 concentrations corresponding to 100, 50, 25, 12.5, 6.25, 3.13, 1.56and 0.78 μM at incubation. For the positive controls (bacterial growth)and negative controls (blank/sterility control) in the wells with twocolumns, 100 μl/well of TSB without compounds were distributed.

Execution of the Test

The incubation was initiated by dispensing 100 μl/well of the bacterialsuspension, using a multi-channel pipette, into the columns containingtest compounds, reference macrolides and positive control. 100 μl of TSBwere dispensed in the sterility control/blank column.

The bacterial growth was measured by reading the absorbance at 570 nmusing a 96-well plate reader. The readings were taken at the start ofthe incubation and every 30 minutes from 2 hours up to 5 hours ofincubation.

Evaluation of the Data

The absorbance values for each well, measured at the start of theincubation, were subtracted from the readings taken at the subsequentincubation times. From the values obtained, the inhibitions werecalculated as a percentage of lack of bacterial growth relative to 100%growth measured in the uninhibited control wells at the respectiveincubation times. The values of the concentrations that inhibit thebacterial development by 20%, 50% and 80% (IC 20, 50, 80%) werecalculated using at least 3 incubation times for which the increase inabsorbance appeared to be the most linear among the concentrations(generally between 150 and 240 minutes of incubation). For each selectedtime, by using the paired series of concentrations and inhibitions, theinhibiting concentrations were calculated by means of a sigmoidal fit.The values of the inhibiting concentrations indicated are the mean ofthe values calculated for at least three selected incubation times. Forthe inactive compounds, an IC >100 is indicated, meaning that at themaximum test concentration (100 μM), no inhibition could be calculated.

The results obtained for the reference antibiotic macrolides and for thecompounds of formula I, expressed in nmol/ml of the concentrations (IC)that inhibit the growth of the bacterial strain Escherichia coli (ATCC25922) by 20, 50 and 80%, are given in Table 2 below:

TABLE 2 Compound IC 20% IC 50% IC 80% Erythromycin 3.0 7.8 24.3Telithromycin 2.7 5.7 14.9 1 >100 >100 >100 2 >100 >100 >100The data given in Table 2 clearly indicate that the compounds of formulaI, which are the object of the present invention, are substantially freeof antibiotic activity.

1. Compound of formula

in which R₁ is a group —X—R₃ in which X is a group —C(═O)—, —C(═O)—O—,—C(═O)—N—, —SO₂— or —SO₂—N— and R₃ is a hydrogen atom; a (C₁-C₁₀)alkylgroup; a (C₁-C₄)alkoxy-(C₁-C₄)alkyl group; a (C₅-C₇)cycloalkyl group; aphenyl, a five- or six-membered heteroaryl containing from one to threeheteroatoms chosen from nitrogen, oxygen and sulfur, aphenyl(C₁-C₄)alkyl group or a heteroaryl(C₁-C₄)alkyl group optionallysubstituted with 1 to 3 substituents chosen from a (C₁-C₄)alkyl group, a(C₁-C₄)alkoxy group and halogen; or a chain of formula—(CH₂)_(r)—Y—(CH₂)_(m)-A in which A is a phenyl or a five- orsix-membered heteroaryl containing from one to three heteroatoms chosenfrom nitrogen, oxygen and sulfur, both optionally substituted with 1 to3 substituents chosen from a (C₁-C₄)alkyl group, a (C₁-C₄)alkoxy groupand halogen; or a group

in which R₄ and R₅, independently of each other, are a hydrogen atom, a(C₁-C₆)alkyl group, a benzyl, a (C₁-C₄)alkoxy-carbonyl group or abenzyloxycarbonyl group; Y represents O, S or NR₆ in which R₆ is ahydrogen atom, a linear or branched (C₁-C₃)alkyl, a(C₁-C₃)alkoxycarbonyl group or a benzyloxycarbonyl group; r is aninteger between 1 and 3; m is an integer between 0 and 3; R₂ is ahydrogen atom, a (C₁-C₆)alkyl group, a benzyl group or has the meaningsgiven for the substituent R₁, and pharmaceutically acceptable saltsthereof.
 2. Compound according to claim 1, in which R₂ is a hydrogenatom, a (C₁-C₆)alkyl group or a benzyl group.
 3. Compound according toclaim 2, in which R₂ is a (C₁-C₃)alkyl group.
 4. Compound according toclaim 3, in which R₁ is a group —X—R₃ in which X is a group —C(═O)—,—C(═O)—N— or —SO₂— and R₃ is a hydrogen atom; a (C₁-C₆)alkyl group; a(C₁-C₄)alkoxy(C₁-C₄)alkyl group; a (C₅-C₇)cycloalkyl group; a phenyl, afive- or six-membered heteroaryl containing from one to threeheteroatoms chosen from nitrogen, oxygen and sulfur, aphenyl(C₁-C₄)alkyl group or a heteroaryl(C₁-C₄)alkyl group optionallysubstituted with 1 to 3 substituents chosen from a (C₁-C₄)alkyl group, a(C₁-C₄)alkoxy group and halogen; or a chain of formula—(CH₂)_(r)—Y—(CH₂)_(m)-A in which A is a phenyl or a five- orsix-membered heteroaryl containing from one to three heteroatoms chosenfrom nitrogen, oxygen and sulfur, both optionally substituted with 1 to3 substituents chosen from a (C₁-C₄)alkyl group, a (C₁-C₄)alkoxy groupand halogen; or a group

in which R₄ and R₅, independently of each other, are a hydrogen atom, a(C₁-C₄)alkyl group or a benzyl; Y represents O, S or NR₆ in which R₆ isa hydrogen atom or a (C₁-C₃)alkyl group; r is an integer between 1 and3; and m is an integer between 0 and
 3. 5. Compound according to claim4, in which R₁ is a group —X—R₃ in which R₃ is a (C₁-C₆)alkyl group; amethoxy(C₁-C₃)alkyl group; a (C₅-C₇)cycloalkyl group; a phenyl, aheteroaryl chosen from furan, thiophene, oxazole and pyridine, a benzylor heteroaryl(C₁-C₄)alkyl group optionally substituted with 1 to 3substituents chosen from a (C₁-C₄)alkyl group, a methoxy group andhalogen; or a chain of formula—(CH₂)_(r)—Y—(CH₂)_(m)-A in which A is a phenyl or a heteroaryl chosenfrom furan, thiophene, oxazole and pyridine, both optionally substitutedwith a substituent chosen from a (C₁-C₄)alkyl group, a methoxy group andhalogen; or a group;

in which R₄ and R₅, independently of each other, are a hydrogen atom ora (C₁-C₄)alkyl group; Y represents O, S or NR₆ in which R₆ is a hydrogenatom; r is an integer between 1 and 3; and m is an integer between 0 and2.
 6. Compound according to claim 5, in which R₁ is a group —X—R₃ inwhich X is a group —C(═O)— and R₃ is a (C₁-C₄)alkyl group or a phenyl.7. Compound of formula I in which R₂ is a methyl and R₁ is a group —X—R₃in which X is a group —C(═O)— and R₃ is a methyl.
 8. Compound of formulaI in which R₂ is a methyl and R₁ is a group —X—R₃ in which X is a group—C(═O)— and R₃ is a phenyl.
 9. Process for preparing a compound offormula I, which comprises: a. demethylation of the dimethylamino groupof telithromycin in position 3′; b. amidation reaction of the primary orsecondary amine group thus formed as a product of the reaction in pointa.
 10. Pharmaceutical composition containing a therapeutically effectiveamount of a compound according to claim 1 mixed with a pharmaceuticallyacceptable carrier.
 11. Pharmaceutical composition according to claim10, which is useful for treating inflammatory pathologies. 12.Pharmaceutical composition according to claim 11, which is useful fortreating respiratory pathologies.
 13. Pharmaceutical compositionaccording to claim 11, which is useful for treating gastrointestinalpathologies.